Exercism: Bob (Elm)

A presentation outlining my solution to the Exercism Bob problem in Elm (https://exercism.io/tracks/elm/exercises/bob).

Presented at the Sydney Elm meetup on 26 September 2019.

Presentation slide deck markdown and speaker notes (useable in Deckset 2):
https://github.com/paulfioravanti/presentations/tree/master/exercism_elm_bob

Transcript

1. Bob
4. Bob
7. ! "Sure."
8. ! "Sure." ! "Whoa, chill out!"
9. ! "Sure." ! "Whoa, chill out!" ! "Calm down, I know what I'm doing!"
10. ! "Sure." ! "Whoa, chill out!" ! "Calm down, I know what I'm doing!" ! "Fine. Be that way!"
11. ! "Sure." ! "Whoa, chill out!" ! "Calm down, I know what I'm doing!" ! "Fine. Be that way!" ! "Whatever."
12. Bob
13. Bob
14. Bob ! Dis$nguish ques$ons
15. Bob ! Dis$nguish ques$ons ! Dis$nguish yelling
16. Bob ! Dis$nguish ques$ons ! Dis$nguish yelling ! Dis$nguish a ques$on yelled
17. Bob ! Dis$nguish ques$ons ! Dis$nguish yelling ! Dis$nguish a ques$on yelled ! Understand silence
18. Bob ! Dis$nguish ques$ons ! Dis$nguish yelling ! Dis$nguish a ques$on yelled ! Understand silence ! Provide a fallback
19. ! Take 1
20. module Bob exposing (hey) hey : String -> String hey message =
21. Dis$nguish Silence hey : String -> String hey message = if isSilence message then "Fine. Be that way!"
22. Dis$nguish Silence hey : String -> String hey message = if isSilence message then "Fine. Be that way!" isSilence : String -> Bool isSilence message = String.trim message == ""
23. Dis$nguish a Ques$on Yelled hey : String -> String hey message = if isSilence message then "Fine. Be that way!" else if isYelling message && isQuestion message then "Calm down, I know what I'm doing!"
24. Dis$nguish a Ques$on Yelled hey : String -> String hey message = if isSilence message then "Fine. Be that way!" else if isYelling message && isQuestion message then "Calm down, I know what I'm doing!" isYelling : String -> Bool isYelling message = (String.toUpper message == message)
25. Dis$nguish a Ques$on Yelled hey : String -> String hey message = if isSilence message then "Fine. Be that way!" else if isYelling message && isQuestion message then "Calm down, I know what I'm doing!" isYelling : String -> Bool isYelling message = (String.toUpper message == message) && not (onlyDigitsOrNonWords message)
26. Dis$nguish a Ques$on Yelled isYelling : String -> Bool isYelling message = (String.toUpper message == message) && not (onlyDigitsOrNonWords message) onlyDigitsOrNonWords : String -> Bool onlyDigitsOrNonWords message = let regex = "^([0-9]|[^a-zA-Z])+$" |> Regex.fromString |> Maybe.withDefault Regex.never in Regex.contains regex message
27. Dis$nguish a Ques$on Yelled hey : String -> String hey message = if isSilence message then "Fine. Be that way!" else if isYelling message && isQuestion message then "Calm down, I know what I'm doing!"
28. Dis$nguish a Ques$on Yelled hey : String -> String hey message = if isSilence message then "Fine. Be that way!" else if isYelling message && isQuestion message then "Calm down, I know what I'm doing!" isQuestion : String -> Bool isQuestion message = message |> String.trim |> String.endsWith "?"
29. Dis$nguish Yelled Ques$on hey : String -> String hey message = if isSilence message then "Fine. Be that way!" else if isYelling message && isQuestion message then "Calm down, I know what I'm doing!"
30. Dis$nguish Yelling hey : String -> String hey message = if isSilence message then "Fine. Be that way!" else if isYelling message && isQuestion message then "Calm down, I know what I'm doing!" else if isYelling message then "Whoa, chill out!"
31. Dis$nguish Ques$ons hey : String -> String hey message = if isSilence message then "Fine. Be that way!" else if isYelling message && isQuestion message then "Calm down, I know what I'm doing!" else if isYelling message then "Whoa, chill out!" else if isQuestion message then "Sure."
32. Provide a Fallback hey : String -> String hey message = if isSilence message then "Fine. Be that way!" else if isYelling message && isQuestion message then "Calm down, I know what I'm doing!" else if isYelling message then "Whoa, chill out!" else if isQuestion message then "Sure." else "Whatever."
36. exercism submit Bob.elm
37. Done!
38. Done?
40. ! Repe$$on in condi$on checking
41. ! Repe$$on in condi$on checking ! Repe$$on with String.trim
42. ! Repe$$on in condi$on checking ! Repe$$on with String.trim ! Do we really need a regex?
43. ! Repe$$on in condi$on checking ! Repe$$on with String.trim ! Do we really need a regex? ! Big if statements don't feel right
44. ! Take 2
45. Dis$nguish Silence hey : String -> String hey input =
46. Dis$nguish Silence hey : String -> String hey input = let message = String.trim input
47. Dis$nguish Silence hey : String -> String hey input = let message = String.trim input isSilence = message == ""
48. Dis$nguish Silence hey : String -> String hey input = let message = String.trim input isSilence = message == "" in if isSilence then "Fine. Be that way!" else respondToVerbalMessage message
49. Dis$nguish Ques$on respondToVerbalRemark : String -> String respondToVerbalRemark message =
50. Dis$nguish Ques$on respondToVerbalRemark : String -> String respondToVerbalRemark message = let isQuestion = String.endsWith "?" message
51. Dis$nguish Ques$on respondToVerbalRemark : String -> String respondToVerbalRemark message = let isQuestion = String.endsWith "?" message hasLetters = String.any Char.isAlpha message
52. Dis$nguish Yelling respondToVerbalRemark : String -> String respondToVerbalRemark message = let isQuestion = String.endsWith "?" message hasLetters = String.any Char.isAlpha message isYelling = hasLetters && String.toUpper message == message
53. Dis$nguish Ques$on/Yelling Combos respondToVerbalRemark : String -> String respondToVerbalRemark message = let -- ... in case ( isQuestion, isYelling ) of
54. Dis$nguish Ques$on/Yelling Combos respondToVerbalRemark : String -> String respondToVerbalRemark message = case ( isQuestion, isYelling ) of ( True, True ) -> "Calm down, I know what I'm doing!"
55. Dis$nguish Ques$on/Yelling Combos respondToVerbalRemark : String -> String respondToVerbalRemark message = case ( isQuestion, isYelling ) of ( True, True ) -> "Calm down, I know what I'm doing!" ( True, False ) -> "Sure."
56. Dis$nguish Ques$on/Yelling Combos respondToVerbalRemark : String -> String respondToVerbalRemark message = case ( isQuestion, isYelling ) of ( True, True ) -> "Calm down, I know what I'm doing!" ( True, False ) -> "Sure." ( False, True ) -> "Whoa, chill out!"
57. Dis$nguish Ques$on/Yelling Combos respondToVerbalRemark : String -> String respondToVerbalRemark message = case ( isQuestion, isYelling ) of ( True, True ) -> "Calm down, I know what I'm doing!" ( True, False ) -> "Sure." ( False, True ) -> "Whoa, chill out!" ( False, False ) -> "Whatever."
59. You'll rarely get it right the first *me
60. Submit o)en, get feedback
61. Read other people's code
62. Refactor un,l you're happy
63. github.com/paulfioravanti/exercism
64. Thanks! @paulfioravanti